Clean up amp-inabox feature flag. (ampproject#7606)

* Clean up amp-inabox feature flag.

* add back config.

src/inabox/amp-inabox.js

@@ -39,7 +39,6 @@ import {
 import {cssText} from '../../build/css';
 import {maybeValidate} from '../validator-integration';
 import {maybeTrackImpression} from '../impression';
-import {isExperimentOn} from '../experiments';
 import {installViewerServiceForDoc} from '../service/viewer-impl';
 import {installInaboxViewportService} from './inabox-viewport';
 import {installAnchorClickInterceptor} from '../anchor-click-interceptor';
@@ -78,12 +77,10 @@ startupChunk(self.document, function initial() {
       installRuntimeServices(self);
       fontStylesheetTimeout(self);
 
-      if (isExperimentOn(self, 'amp-inabox')) {
-        // Install inabox specific Viewport service before
-        // runtime tries to install the normal one.
-        installViewerServiceForDoc(ampdoc);
-        installInaboxViewportService(ampdoc);
-      }
+      // Install inabox specific Viewport service before
+      // runtime tries to install the normal one.
+      installViewerServiceForDoc(ampdoc);
+      installInaboxViewportService(ampdoc);
 
       installAmpdocServices(ampdoc);
       // We need the core services (viewer/resources) to start instrumenting

tools/experiments/experiments.js

@@ -92,12 +92,6 @@ const EXPERIMENTS = [
     spec: 'https://github.com/ampproject/amphtml/issues/6196',
     cleanupIssue: 'https://github.com/ampproject/amphtml/issues/6217',
   },
-  {
-    id: 'amp-inabox',
-    name: 'AMP inabox',
-    spec: 'https://github.com/ampproject/amphtml/issues/5700',
-    cleanupIssue: 'https://github.com/ampproject/amphtml/issues/6156',
-  },
   {
     id: 'amp-form-var-sub',
     name: 'Variable Substitutions in AMP Form inputs for POST/GET submits',